This invention relates to an apparatus for diagnosing malfunction and, more particularly, to a diagnostic apparatus applicable to diagnose misfire in an internal combustion engine.
For example, Japanese Patent Kokai No. 4-9635 discloses an engine misfire diagnostic apparatus which provides a diagnostic result indicating whether misfire for accured in one or more engine cylinders. The apparatus diagnoses misfire in one engine cylinder to provide a first indication that misfire occurs in a single cylinder and, then, it diagnoses misfire in another engine cylinder to provide a second indication that misfire has occured in a plurality of engine cylinders. With the conventional diagnostic apparatus, however, the first indication remains after the second indication is provided. For the simultaneous indications, the serviceman would repair the one engine cylinder and leave the other cylinder as it is.